We propose a randomized controlled trial to adapt, implement and evaluate an intervention to prevent HIV/STI in young heterosexual Latino couples. The intervention consists of five three-hour sessions held once a week. We will use a group format to deliver the intervention with the couples. This was a successful strategy used in our previous study. The study is designed to test the impact of the modified intervention in: (1) increasing male condom use, (2) decreasing unsafe sex behaviors, (3) reducing the number of sexual partners;and (4) increasing mutual monogamy. The couples will be randomized to one of the following two conditions: (1) an HIV/STI risk reduction intervention;or (2) a life skills intervention, as control condition. The study will be carried out in two phases. Phase 1 will consist of the adaptation of an intervention designed and implemented by the PI research team. For the adaptation of the intervention we will use the ADAPT-ITT model which consists of eight phases: (1) assessment;(2) decision;(3) adaptation;(4) production;(5) topical experts;(6) integration;(7) training;and (8) testing. During this phase we will conduct focus groups, "theater testing" and a pilot of the intervention. These activities will help to explore crucial feedback and recommendations about the content of the intervention that need to be modified, according to participant's recommendations. During Phase 2 we will implement the modified intervention with 75 young heterosexual Latino couples (150 individuals) at-risk of HIV/STI infection. At this stage hierarchical modeling and mixed-effects regression analysis will be conducted to determine if the intervention accomplished the expected main outcome in increasing male condom use and decreasing unsafe sex behaviors. This project is of great relevance for public health because: (a) it will be the first known prevention intervention designed and implemented with young heterosexual Latino couples;(b) it will address previous methodological limitations by using a rigorous RCT design to test the efficacy of the intervention in increasing self-reported condom use over a 3-month follow-up period among 75 Latino couples;(c) it will test the efficacy of using a group format for the implementation of the intervention with couples;(d) it will employ a sequential approach in which couples will benefit from gender-specific sessions as well as mixed-gender sessions;and (e) it is the only known intervention with Latino couples that is based on the Information-Motivation-Behavioral Skills model of behavior change.